This invention relates to a solid state light source. It relates particularly to such a light source which is capable of emitting light over a broad spectral band.
In the construction of optical fibre devices which make use of a spectral filtering technique, it is usual to employ tungsten-halogen incandescent filament lamps in order to provide the broad spectral emission width that is necessary. Unfortunately, the filament lamp is a somewhat fragile article and this characteristic makes it unreliable in operation. The need to include such a lamp is likely to cause eventual breakdown of the complete fibre device particularly when this is used under the severe conditions of operation that are sometimes necessary. The degree of ruggedness and reliability that would be desirable in the lamp part can be found in the light emitter diode construction but these devices have inherently a rather narrow spectral emission width (typically 40 nanometers at a wavelength of 900 nanometers) so that a single conventional LED would be incapable of providing the bandwidth required.
One object of the present invention is to provide a solid state light source that will be capable of emitting light over a broad spectral band and which will be reliable in operation.